1. Field of the Invention
The subject invention relates to gaskets for use in static sealing applications, such as engine, transmission, axle, other similar powertrain sealing applications, and more specifically to gaskets for use in sealing multiple fluids.
2. Description of the Related Art
Injection molded gaskets fabricated of rubber and the like are known for installation within an engine for sealing fluids and preventing leaks. The related art gaskets are typically formed from a first material and a second material spaced from one another and these materials are supported on a carrier. During formation, the materials are formed in a mold separate from one another such that the materials are not in contact. Most typically, one material is formed first and then the second material is formed thereafter. The first and the second materials are generally elastomeric or thermoset materials.
These first and second materials cure at different rates. Once one material has completely cured, it is very difficult to have another material bond to the cured material without the use of additional adhesives, or bonding agents. If additional adhesives are used between the materials, then the bond that is formed between the cured material and the adhesive is weak. Thus, the gasket has an increased likelihood of failing at the bond where the adhesive is located. Such failure of the gasket results in leakage of the fluids which may result in damage to the engine.
It is well known that certain materials are better suited to seal certain fluids than are other materials. For example, a hydrogenated nitrile rubber elastomer is particularly suited for sealing a coolant fluid and fluoroelastomer is particularly suited for sealing an air/fuel mixture. While each of these materials may seal the other fluid, they are not best suited to do so and may result in premature failure. Manufacturers of gaskets to seal multiple fluids have sacrificed the ability to seal the fluids by employing a single material that is not best suited for any of the fluids. As an illustration, it is common to use silicone materials on a gasket to simultaneously seal three fluids, namely, an air/fuel mixture, a coolant, and oil. As engine performance and demands continue to increase, the gaskets are exposed to higher temperatures and to a more chemically aggressive environment. Such silicone materials may continue to work to seal multiple fluids; however, these higher temperatures and increasingly chemically aggressive environments will shorten the useful life of such gaskets that have materials that are not suited for such applications.